After asking Alptraum about what his shadow has done – with and without his guidance – the Countess explains how it can be used as a garment or second skin, and the sort of defensive abilities it infers through the dulling of senses.

Alptraum masters the basics quickly enough, and when Draco touches him with her own shroud there is a surprising effect – which results in the lesson being cut a bit short in order to 'experiment' with that a bit further.